From a novelist's point of view, Tolstoy was right: unhappy, dysfunctional families are easier to make compelling than happy ones. To portray a family in good emotional shape in a way that is unsentimental and holds the attention takes real skill and judgment. One of the joys of Binny for Short is how McKay constructs a convincing, page-turning portrait of a loving family that copes with adversity and whose members support and relate to one another. The chief weapons in her armoury are comedy and a gift for characters that leap off the page.

Bin, Bel, Belinda – Binny for short – moves to a small house by the seaside with her mother, elder sister Clem and six-year-old James. While turning weak-kneed over the golden-skinned brother of Clem's best friend, Binny actually spends most of her time with Gareth, there under sufferance with his father and future stepmother. Binny and Gareth are best enemies: "With Gareth nothing was needed. No admiration, no tact, no caution, no politeness, no responsibility in any way. Never before had Binny had such a perfect companion: so handy, so alien, so entirely insensitive that she didn't have to bother about his feelings at all."

Two parallel narratives shape the novel and dovetail by the end. One tells the story of Binny and Gareth's perilous attempt to remove a huge barbed fishing net from waters inhabited by seals. The other, primary narrative provides the family's backstory: the sudden death of the father, the subsequent loss of income, of family home, of lifestyle. The mother, uncomplaining and cheerful, struggles to keep her family afloat: finding accommodation, looking after the youngest, getting part-time work in an old people's home. As admirable a character as the mother in The Railway Children – high praise indeed – "she was brave, and she had a way of making other people feel brave, as well".

Being the family they are, everyone adjusts. The youngest plays happily in his own little world of spider farms and poisonous cress beds. The eldest works to pay for flute lessons. Binny, however, pines for her dog, sent to a new home by the hateful Aunty Violet. A standoff between Binny and Violet at the grandmother's funeral results in an unexpected outcome: Violet dies soon after and leaves her seaside home to the family, sending "particular regards" to Binny. At the heart of the novel is McKay's perceptive exploration of Binny's feelings towards two people: her "enemy" Gareth and Violet, whose presence haunts her and whom, of course, she resembles in more ways than one.

As always, the family is McKay's focus. She writes of gilded youth ("so flawless [Clem] seemed to radiate a cool light"), and the solidarity between the very old and the very young ("The old ladies lived lives of delicious selfishness. [...] They understood [James] down to his bones").

A past winner of the Whitbread and the Guardian children's fiction prize, McKay plays to her strengths in this nourishing and tremendously entertaining novel: she uses a small canvas and observes closely; her voice is warm, wise and witty; her language is economical and precise. Binny for Short shows a mistress of her medium at work.

• Linda Buckley-Archer's Time Quake Trilogy is published by Simon & Schuster.